Techniques for the production of a hard copy from soft information may be used because of recent progress which has been made with information processing and storage techniques and with techniques for image processing, and because of the availability of communication circuits. On the other hand, very high quality photographic prints can be made comparatively easily and inexpensively because of the progress which has been made with silver halide photosensitive materials and compact, rapid, simple development systems (for example, the mini-laboratory system). Furthermore, there is a great demand for an inexpensive hard copy which can be made easily from soft information with the high picture quality of photographic prints.
In the past, techniques for making hard copy from soft information have included those in which no photosensitive recording materials are used (such as those involved in the systems in which electrical signals and electromagnetic signals are used and ink jet systems) and those in which photosensitive materials, for example, silver halide photosensitive materials and electrophotographic materials, are used. In the latter category of techniques, there are systems in which recordings are made with an optical system which emits light under control in accordance with the image information. This enables not only optical system production, image resolution and binary recording but also multi-gradation recording to be achieved. These systems are useful for obtaining high image quality. The silver halide photosensitive materials are more convenient than systems in which electrophotographic materials are used since image formation is achieved chemically. On the other hand, systems in which silver halide photosensitive materials are used must have photosensitive wavelengths which match the optical system, stable photographic speeds, latent image stability, resolving power, separation of the three primary colors, and rapid and simple color development processing characteristics. Finally, attention must be given to cost.
In the past, copying machines and laser printers were used in which electrophotographic techniques were used. Color copying techniques include silver halide based heat developable dye diffusion systems, and "Pictography" (a trade name of Fuji Photo Film Co., Ltd.) in which LED's are used.
Color photographic materials comprising a support having thereon at least three silver halide emulsion layers which contain normal color couplers and which are not exposed to visible light, wherein at least two of the layers are sensitized to laser light in the infrared region, and the fundamental conditions for these materials, have been disclosed in the specification of JP-A-61-137149. (The term "JP-A" as used herein signifies an "unexamined published Japanese patent application".)
Full color recording materials are known which comprise a support having thereon a unit of at least three photosensitive layers which contain color couplers, wherein at least one layer is prepared so that it is photosensitive to a LED or a semiconductor laser light. They are spectrally sensitized so that the spectrally sensitized peak wavelength is longer than about 670 nm. With this material colored images can be obtained by means of a light scanning exposure and a subsequent color development process. A method of spectral sensitization which is stable and provides high speed, a method of using dyes and such a full color recording material have been disclosed in the specification of JP-A-63-197947.
A color photographic material color image recording system wherein yellow, magenta and cyan color formation is controlled with three light beams which have different wavelengths, for example green, red and infrared light beams respectively, has been disclosed in the specification of JP-A-55-13505.
The basic conditions for a continuous tone scanning type printer semiconductor laser output controlling mechanism have been described by S.H. Baek on pages 245-247 of the published papers in the Fourth International Symposium on Non-impact Printing (NIP) (SPSE).
However, there is no suggestion in the above-mentioned literature of sensitizing dyes which have the specified crosslinking structure of the present invention.
Means in which non-photosensitive recording materials are used to obtain hard copy from soft information are effective for low image quality results. But it is virtually impossible to obtain photographic print type picture quality with the A4 to B4 or smaller sizes which are normally used. Even though the cost per sheet is low, the cost is high when picture quality (for example, recording content-density.times.surface area) is taken into account. The image quality with electro-photographic systems is worse than that obtained with silver halide photosensitive material systems. Further, the image forming process is more complex mechanically, and it is difficult to obtain hard copies of high picture quality in a stable manner.
On the other hand, stable high picture quality is readily obtained with systems in which silver halide photosensitive materials are used. But the photosensitive materials themselves must be provided with photosensitive wavelengths which match the optical system, stable photographic speed, latent image stability, and separation of the three primary colors. Silver iodobromide emulsions, silver bromide emulsions and silver chlorobromide emulsions are known as silver halide emulsions which can be used in silver halide photographic materials which are to be written-in by laser light beams. The color development process of these full color recording materials is preferably rapid, taking not more than 60 seconds, in order to match the speed of write-in with an output device in which semiconductor laser beams are used. Silver halide emulsions which have a high silver chloride content are useful for this purpose. In general, infrared sensitization to wavelengths beyond 670 nm and especially to wavelengths longer than 750 nm is difficult. Furthermore, there are other difficulties with silver chlorobromide emulsions which have a high silver chloride content, especially those which have a silver chloride content of more than 95 mol %. First, they have poor photographic speed and stability during manufacture and storage. It is especially difficult to obtain a gradation which has good linearity at high photographic speeds. Furthermore, it is difficult to obtain a sharp spectral sensitivity distribution. Second, it is difficult to obtain high photographic speeds with short exposures times, for example with 10.sup.-6 -10.sup.-8 second exposures. Third, dissolution of the emulsion, loss of photographic speed with aging and the occurrence of fogging are likely to occur when absorption on the silver halide grains is poor, especially in the presence of color couplers, high concentrations of surfactants and organic solvents. Hence, the development of sensitive materials which have high speed and which have excellent latent image stability, even though infrared sensitized silver halide emulsions are being used, is desirable. Furthermore, the development of sensitive materials in which high silver chloride emulsions which can be processed rapidly are used is especially desirable.